A general method for the preparation of zirconocene complexes of imines has been developed. The X-ray crystal structure of the (trimethylsilyl)benzaldimine complex 2b shows that these complexes should be viewed as metallaziridenes due to significant π-donation from the zirconium center to the π* orbitals of the coordinated imine. These complexes undergo a number of chemo-, region-, and diastereoselective coupling reactions with unsaturated organic compounds to cleanly form metallacyclic compounds. In situ generation of the complexes followed by coupling with alkynes and hydrolysis affords a general route to geometrically pure allylic amines.
“Zirconocene complexes of imines. General synthesis, structure, reactivity, and in situ generation to prepare geometrically pure allylic amines”, J. Am. Chem. Soc., 1989, 111(12), 4486-4494.